With the development of the wireless network technology, the application of the wireless network in people's life is more and more extensive. The wireless internet access of the laptop has already become a trend, but the coverage of the wireless fidelity (abbreviated as WiFi) hotspot is too low and limits the space of wireless internet access of the laptop to a certain extent. The data card adopting the 3rd generation (abbreviated as 3G) network can remedy the defect to a great extent, and the data card makes people perform the online entertainment and even the online working freely at the places without the WiFi hotspot, such as, the bus, the hotel, even the open country, etc. But in the environment where there is no active power and only the battery-power can be used, the power consumption of the data card (that is, the wireless internet access data card) is a huge challenge for the standby time of the laptop, and therefore how to reduce the power consumption of the data card device to the greatest extent becomes a problem urgently to be solved.
The number of modules of the data card which can save electricity is originally few and the space of the electricity saving was not big, and the USB, as the essential part, can achieve the electricity saving, which will reduce the power consumption of the data card to a certain extent and lengthen the standby time of the laptop as well.
After the data card is inserted into the laptop, besides virtualizing the COM port used for the user to access the internet, it also will virtualize the CDROM with the important file, such as, the internet access software and the device driver which is necessary for the user to use the data card, etc., for using by the user. The USB protocol stipulates that, when the USB bus is idle, that is, there is not any signal, the host will initiate the Suspend signal voluntarily after 3 ms, to notify the USB controller at the card side to enter the suspend state, thus reducing the power consumption of the device. But the Mass Storage protocol stipulates that the host will constantly send the device detection instruction, to require the device to perform responding. In this way, the USB bus will generate the signals all the time, and the USB is unable to enter the suspend mode, which cannot achieve the effect of the electricity saving. FIG. 1 shows the process of the interaction between the data card with the CDROM and the personal computer (abbreviated as PC) in the related art.
In step S102, the data card is inserted into the PC.
In step S104, the PC enumerates the CDROM, and installs the corresponding drivers and the internet access software at PC side automatically; the user pops up the CDROM manually, and the PC enumerates the CDROM and the COM port again.
In step S106, the PC sends the Test Unit Ready command (even if there is no network data transmission) to the Device constantly according to the enumerated CDROM (USB Mass Storage) device.
In step S108, the software at PC side does not intervene to the interaction of the PC and the Device in that process.
In step S110 and step S112, the Device responds to the PC, and there is the data transmission all the time in the USB bus.
In step S114, the UEB does not enter the Suspend, and because there is the data transmission in the USB bus, the PC does not generate the USB Suspend, and the USB does not enter the power saving mode.
So, how to solve the contradiction between the two becomes a key problem to solve that the USB can enter the suspend state when there is the read-only memory (CDROM).
The effective solution has not been put forward yet at present aiming at the above-mentioned problem in the related art.